Difference between revisions of "Team:UMaryland/Results"

Revision as of 02:54, 19 September 2015

Plating Tests - Counting Colonies to Confirm Chloramphenicol Resistance

Over time, all cultures appeared to maintain antibiotic resistance, except for the negative control, which experienced no pressure during its growth. The following figures demonstrate the presence of resistant colonies over many hundreds of bacterial generations. Most importantly, the Hok-Sok culture grown without antibiotic was shown to maintain chloramphenicol resistance. This sets up one of our major conclusions: the Hok-Sok cassette is capable of maintaining a recombinant plasmid for an extended period of time.

Negative Control (No Pressure)

Figure 1. Negative control was K1783002 (constitutive unstable RFP) grown in media without chloramphenicol. After 2-3 days, plates demonstrate fewer than 10 colonies per plate, suggesting that antibiotic resistance is now only minimally present in the culture.

Chloramphenicol Pressure Only

Figure 2. K1783002 (constitutive unstable RFP) grown in media with chloramphenicol. Colonies persist through several days of plating, suggesting that antibiotic resistance was maintained throughout the test.

Chlor + Hok-Sok Pressure

Figure 3. K1783003 (constitutive unstable RFP under Hok-Sok regulation) grown in media with chloramphenicol. Colonies persist through several days of plating, suggesting that antibiotic resistance was maintained throughout the test.

Hok-Sok Pressure Only

Figure 4. K1783003 (constitutive unstable RFP under Hok-Sok regulation) grown in media without chloramphenicol. Colonies persist through several days of plating, suggesting that antibiotic resistance was maintained throughout the test.

Growth Curve <

Figure 5. Growth curves of parallel cultures grown with and without chloramphenicol. The presence of Hok-Sok on the inserted plasmid does not appear to have a major effect on the bacterial growth rate. This is in line with our qualitative observations, where we do not observe any major difference in cell density during plating or fluorescence studies.

Fluorescence Studies

DH5α Cell Line

Figure 6. Fluorescence measurements of K1783002 (Constitutive unstable RFP) in DH5α cells grown in media containing antibiotic. All measurements are blank-subtracted. Fluorescence is initially high, but rapidly diminishes over time.

Figure 7. K1783002 (Constitutive unstable RFP) in DH5α cells grown in media without antibiotic. Fluorescence is initially low and rapidly diminishes over time. This result supports the notion that cells grown without any pressure quickly lose their plasmids.

Figure 9. K1783003 (Hok-Sok+Constitutive unstable RFP) in DH5α cells grown in media with antibiotic. Fluorescence is initially moderate and diminishes over time. The use of two maintenance systems does not appear to better maintain fluorescence levels than chloramphenicol alone. We suggest that the proximity of the Hok-Sok cassette to the RFP construct somewhat represses expression of RFP due to promoter interference, leading to a lower initial reading.

Figure 9. K1783003 (Hok-Sok+Constitutive unstable RFP) in DH5α cells grown in media without antibiotic. Fluorescence is initially moderate, but remains relatively constant over time, a one-time spike notwithstanding.

BL21 Cell Line

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 <p style="font-size:48px;text-align:center;font-family:Verdana, Geneva, sans-serif;"><b>Growth Curve</b>
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 <p><img src = "https://static.igem.org/mediawiki/2015/3/37/UMDGrowthCurve2.png"></p>
 <p style = "font-size:18px">Figure 5. Growth curves of parallel cultures grown with and without chloramphenicol. The presence of Hok-Sok on the inserted plasmid does not appear to have a major effect on the bacterial growth rate. This is in line with our qualitative observations, where we do not observe any major difference in cell density during plating or fluorescence studies.</p>
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 <p style="font-size:48px;text-align:center;font-family:Verdana, Geneva, sans-serif;"><b>Fluorescence Studies</b>
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 <img src = "https://static.igem.org/mediawiki/2015/c/c3/FtestChlorUMD.png">
 <p style = "font-size:18px">Figure 6. Fluorescence measurements of K1783002 (Constitutive unstable RFP) in DH5α cells grown in media containing antibiotic. All measurements are blank-subtracted. Fluorescence is initially high, but rapidly diminishes over time.</p>
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 <img src = "https://static.igem.org/mediawiki/2015/d/d5/FtestHSUMD.png">
 <p style = "font-size:18px">Figure 9. K1783003 (Hok-Sok+Constitutive unstable RFP) in DH5α cells grown in media without antibiotic. Fluorescence is initially moderate, but remains relatively constant over time, a one-time spike notwithstanding.</p>
+<p style = "font-size:24px">BL21 Cell Line</p>
+<img src = "https://static.igem.org/mediawiki/2015/c/c1/UMDBL21A.png">
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-<p style="font-size:48px;text-align:center;font-family:Verdana, Geneva, sans-serif;">Future Plans
+<p style="font-size:48px;text-align:center;font-family:Verdana, Geneva, sans-serif;">Conclusions and Future Plans